1. Field of the Invention
The present invention relates to displays in general and in particular to a thin film transistor (TFT) substrate and a flat panel display including the same.
2. Discussion of the Related Art
A flat panel display (FPD) such as a liquid crystal display (LCD) and an organic light emitting diode (OLED) can include a thin film transistor (TFT) substrate on which a thin film transistor (TFT) that is a switching element is formed for active matrix (AM) driving.
The TFT substrate can be divided into a display area and a non-display area that surrounds the display area. A driving circuit that drives the FPD can be mounted on a driving circuit mounting area provided in the non-display area.
The driving circuit can be mounted on the driving circuit mounting area through one of a wire bonding (WB) method, a tape automated bonding (TAB) method, and a chip on glass (COG) method.
In the COG mounting method, the driving circuit including an input bump and an output bump is directly mounted on the TFT substrate. When the driving circuit is mounted on the TFT substrate through the COG method, the input bump and the output bump of the driving circuit can be connected to an input pad electrode and an output pad electrode formed on the TFT substrate. Here, the output pad electrode can be electrically connected to signal lines for driving the display area of the TFT substrate, for example, gate lines and data lines.
Since the input pad electrode and the output pad electrode are separated from each other by the distance between the input bump and the output bump of the driving circuit, an area between the input pad electrode and the output pad electrode can be formed in the driving circuit mounting area.
Recently, in order to improve the usability of the TFT substrate, a technology of forming test patterns for lighting test in the lighting test pattern area has been developed in which a lighting test pattern area is provided in an area between the input pad electrode and the output pad electrode.
However, when the distance between the input bump and the output bump is reduced as the driving circuit is made small, the reduced distance between the input pad electrode and the output pad electrode also reduces the size of the lighting test pattern area.
Therefore, it is very difficult to form the test patterns in the lighting test pattern area whose size is reduced.